GLASS. 



by their weight, pull liuwnvvavcl.s, and c-onrcquently force 

 tlif middle part, relling upon its two props, upwards : and 

 being lefs advanced towards the hre, as being lefs heated, 

 will, by their oblique fituation, pull the middle part back- 

 wards alfo from the Hre, which will caufe a rotatory regrelTive 

 motion, quite contrary to what the tube had when fupportcd 

 near jts extremities. And wlien a fmgle tube lies inclining 

 oppofite to the fire, cither to the right hand or to the left, 

 out of a plane perpendicular to the furface of the fire, gra- 

 vity will not permit the curved part to reft, but pull it 

 down till it coincides with a plane perpendicular to the ho- 

 rizon ; and confequently, as new curves are generated, new 

 motions will be fo too ; that is, the tube will be made to 

 move about its axis, with this difference, when the tube in- 

 clines to the right hand, the niotian will be from eafl to weft ; 

 when to the left hand, from weft to eaft. The juftnefs of 

 this reafoning is made manifeft, by bending a wire, and fup- 

 porting it firft near its extremities, then near its centre on 

 each lide, afterwards incUning it to the right and to llie 

 left ; the bending in every cafe reprefcnting the curved part 

 of the tube next the lire. This folution of the phenomena 

 is rendered the more priibable from hence, that when four 

 fupportera were made ufe of, one at each cxuemity, and two 

 near the middle, there was no motion at all, either backward 

 or forward. Nor does the incrcafe of contaCl hinder the mo- 

 tion, becaufe the plate of glafs was fo broad as to have a 

 much greater contact with the tube, and yet both the rota- 

 tory and regreffive motions were manifeft. 



Thefe experiments fucceeded bell with tubes about twenty 

 or twenty-two inches long ; the diameter about one-tenth 

 of an inch : and they had in each a pretty ftrong piu fixed 

 in cork, for an axis to roll with on the fupporting tubes. 

 Phil. Tranf. N' 476. 



Gt.A.ssi receivers, how to cement the cr,ich of. See C/EMENT 

 and Receiver. 



G1.A.S.S, hoiu to tahe the tmprejfwn of antique gems in. See 

 Gk.m. 



The property which glafs poftelfes in common with other 

 fubftances of being expanded by heat, and contracted by 

 cold, was long ago ohferved and evinced by Mr. Hook. 

 See Birch's Hift of the Royal Society, vol. i. p. 411. See 



TlIKHMOMETER. 



G/>A.s.s, LazL<s relnling to. No glafs fhall be imported 

 into Ireland, other than the manufaft ure of Great Britain, 

 on pain of forfeiting the fame, and ftiip, and loj-. a pound. 

 ig G. II. c. 12. If any foreign glafs fliall be landed or un- 

 (liipjied before entry and payment of the duties, or without 

 warrant from the proper officer, the fame ftiall be forfeited, 

 or its value ; ?md the mafter or other perlbn having command 

 of the veltel, and every other perfon concerned in fuch 

 landing or unlhipping, fliall forfeit 100/. 17 G III. c. 39. 

 And by 38 G. III. c. 33. for preventing the fraudulent 

 importation of glafs, every package containing any plate or 

 plates of glafs unframed, being plate, croivii, or Jlxel glafs, 

 which fliall be imported, or brought into this kingdom for ex- 

 portation, fliall be marked on the outfide in Roman letters 

 four inches long at leaft, with the word Gl-ASS, on pain of 

 forfeiture, together with the package, and all goods con- 

 tained in it. The mafter of the vcflfel importing fuch package, 

 (hall, in reporting his cargo, cxprcfs every fuch package of 

 };lafs, on pain of forfeiting the fame, and alio 100/. Nor 

 (hall any fuch package be imported, which fliall not contain 

 300 wjight, on pain of forfeiture ; but not extending to 

 any p"a e of glafs 60 inches in length or upwards, on account 

 of the package not being marked. By 43 G. III. c. 69. 

 For ev^»ry 100 weight of materials, &c. that fliall be made 

 •vCe of in Great Britain for the making of plate or JJiut glafs. 



or enamel, Jlaineil, or pafe glafs, or phial glafs, fliall be paid hy 

 the maker thereof i/. 12s. be/. ; for every hundred weight of 

 materials ufed in making fpread ivindoiu glafs, commonly 

 called broad glafs, 'is. 2d. ; for every hundred weight of mate- 

 rials ufed for making all other luindow glafs (not being 

 fpread glafs), whether flaflied, or otiierwife manufaClured, 

 commonly called a-own jj-Ai/}, or Gerntanjlieet glafs, ll.^. Gd.; 

 for every hundred weight of materials ufed in making com- 

 mon lollies (noc being phials), and of veflels ufed in che- 

 mical laboratories, and oi garden glajfes, and of all other veffels 

 or utenfils made of common bottle metal, ^j. \d.; and for 

 every hundred weight of plate glals, and of all other glafs 

 manufaftures, which fliall be imported into Great Britain, 

 the fame not being flafl^s, in \\ hich wine or oil is imported, nor 

 foreign green glafs bottles, nor Irifli glafs, or glafs manufac- 

 tures imported direftly from Ireland, to bepaid by the importer 

 before the landing thereof, 2/. 2s. And any glafs-maker fliall 

 take out a licence, for which he fliall pay 10/., to be renewed 

 annually ten days at leaft before the end of the year, on 

 the penalty of 50/. 24 G. III. c. 41. 43 G. III. c. 69. 

 The place of making glafs fliall be entered, before the com- 

 mencement of inanufaclure, and all work-houfe.s, furnaces, 

 pots, annealing arches, &c. &c. on pain of forfeiting 200/. 

 19 G. II. c. 12. 17 G. III. c. 39. 35 G. III. c. 114. 

 Officers may enter and furvey, and mark pots ; and any 

 jierfon counterfeiting or altering fuch mark, or connivino- 

 at its being done, fliall forfeit 500/. ; or defacing, or caufing 

 to be defaced or obliterated fuch mark, incurs a forfeiture of 

 200.'. 35 G. III. c. 1 14. Notice of beginning to work 

 fliall be given in wnting, <m pain of forfeiting 20/. 19 G. II. 

 c. 12. And notice of filhng every pot (hall be given twelve 

 hours before the operation is begun, on pain of 50/. 19 G. II. 

 c. 12. 17 G. III. c. 39. Annealing arches are to be 

 made of a certain form, and numbered, on pain of forfeiting 

 100/. Annealing arches are to be locked, except at certain 

 times ; and breaking fuch lock, &c. incurs a forfeiture of 

 200/. 35 G. III. c. 114. The fame aft comprehends feve- 

 ral other provifions, enforced by certain penalties. BottleS 

 are not to be removed till they are weighed, (penalty ico/. ) 

 which are to be kept feparate from thofe that are unweighecj, 

 on pain of forfeiting 50/. No pliials, &c. are to be made 

 in places entered for making common glafs bottles, on pain' 

 ot forfeiting 200/. Entry fliall be made of the glafs manu- 

 factui-cd every month within the bills, and elfewhere every 

 fix weeks, on pain of 20/. The maker, within the bills, 

 fliall, in four weeks, and elfewhere in fix weeks after entry, 

 pay oft' the duties, on pain of double duty. If glafs, 

 rtiippcd for exportation, Ihall be re-landed, it fliall be for- 

 feited, and every perfon concerned therein fhall forfeit 100/. 

 17 G. III. c 39. For the drawbacks on exportation 

 of glafs, fee 43 6. III. c. 69. Obftrufting officers in fc- 

 curing the duties incurs a forfeiture of jo/. 19 G. II. 

 c. 12. 17 G. III. c. 39. Penalties are appropriated, half 

 to the ufe of the king, and half to him that fliall fue. 



G\..\ii%-Carrich Point, in Geography, a cape -of Ireland, 

 on the eaftern coall of the county of Wexford. N. lat. 

 52^ 35'. W. long. 6 12'. 



Glass-C^, in Gardening, a liglit fort of creftion 

 formed with glafs faflies in proper frame-work, moftly up- 

 right in the front part and ends, but Hoping at top from.;; 

 back wall, or other convenient building, to the fore-part ; 

 the front, toj), and both ends being of glafs-work. The 

 fituation for this purpofe fliovdd face the fouth, in order to 

 have the full influence of the fun, Conflruftions of this 

 nature arc ufeful for protefting many forts of curious tender 

 plants in winter which want it only occalionally from feverc 

 trort, and other' fimilar caufes. 



Buildings 



